1. Technical Field
This invention is directed toward improvements in roll-up closures. This invention is more particularly directed toward a tensioning unit for tensioning the spring in a roll-up closure. The invention is also more particularly directed toward the drum for carrying the hinged door on the closure.
2. Background Art
Roll-up closures are mounted over the opening to be closed by the hinged door of the closure. The closure has an axle which is normally fixedly mounted between end plates fastened to the wall of a building framing the opening. A drum is rotatably mounted on the axle. A hinged door is attached at its top end to the drum and wound up on the drum when the drum is rotated to open the opening. A motor is normally mounted on the axle within the drum to rotate the drum. However the motor could be mounted outside the drum at one end or the drum could also be rotated manually. A tension coil spring is mounted on the axle within the drum with one end of the spring connected to the axle and the other end connected to the drum. The spring is normally initially tensioned when the closure is installed and is further tensioned when the opening is closed by the hinged door, the door unwinding off the drum. The tensioned spring makes it easier for the door to move up when opening the opening. The tension in the spring can be adjusted externally by various known tensioning means.
The known closures have several disadvantages however. The tensioning means employed to adjust the tension in the spring is often mounted outside the end plates making it difficult to employ the closure in tight places. The tensioning means also are quite complicated to use, some requiring two people, some requiring a precarious perch on a ladder. The drum normally employed is cylindrical making it difficult to smoothly roll the hinged door onto the drum. It is also difficult to position and mount elements, such as the drive motor, within the drum.